Question

Problems-1: [2x4=8 pts] Write the general equation governing the photogeneration phenomenon in a PN junction diode. In the equation you should have the current term due to the voltage biasing and the photogenerated current term due to incident light. Mark these terms in your provided equation. Also Answer following questions (1) Draw the I-V current relation (I versus V plot) for changing gop (rate of optical generation). (2) Which quadrant of this I-V relation is utilized for solar-cell applications. (mark in your I- V Curve)? (3) Which quadrant of the I-V relation is utilized for photo-detector application (mark in your I-V curve)? (4) Now consider the photogeneration current term. What will be the effect on photogenerated current, if the P and N sides are highly doped in comparison to light doped. (hint: how depletion region width changes. Also, we are only concerned with the photogenerated terms, not the thermal current or voltage biasing term)

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